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% language=uk
\environment luatex-style
\environment luatex-logos
\startcomponent luatex-introduction
\startchapter[title=Introduction]
This book will eventually become the reference manual of \LUATEX. At the moment,
it simply reports the behaviour of the executable matching the snapshot or beta
release date in the title page. We don't claim it is complete and we assume that
the reader knows about \TEX\ as described in \quotation {The \TEX\ Book}, the
\quotation {\ETEX\ manual}, the \quotation {\PDFTEX\ manual}, etc. Additional
reference material is published in journals of user groups and \CONTEXT\ related
documentation.
Successive versions brought new functionality, more control, some cleanup of
internals and experimental features evolved into stable ones or were dropped.
Already quite early \LUATEX\ could be used for production and it was used in
production by the authors. Successive versions sometimes demanded a adaption to
the \LUA\ interfacing, but the concepts were unchanged. The current version can
be considered stable in functionality and there will be no fundamental changes.
Of course we then can decide to move towards version 2.00 with different
properties.
Don't expect \LUATEX\ to behave the same as \PDFTEX ! Although the core
functionality of that 8 bit engine was starting point, it has been combined with
the directional support of \OMEGA\ (\ALEPH). But, \LUATEX\ can behave different
due to its wide (32 bit) characters, many registers and large memory support.
There is native \UTF\ input, support for large (more that 8 bit) fonts, and the
math machinery is tuned for \OPENTYPE\ math. There is support for directional
typesetting too. The log output can differ from other engines and will likely
differ more as we move forward. When you run plain \TEX\ for sure \LUATEX\ runs
slower than \PDFTEX\ but when you run for instance \CONTEXT\ \MKIV\ it might be
faster on more complex documents. But in any case: 32 bit all||over combined with
more features has a price.
\LUATEX\ consists of a number of interrelated but (still) distinguishable parts.
The organization of the source code is adapted so that it can glue all these
components together. We continue cleaning up side effects of the accumulated
code in \TEX\ engines (especially code that is not needed any longer).
\startitemize[packed]
\startitem
Most of \PDFTEX\ version 1.40.9, converted to C (with patches from later
releases). Some experimental features have been removed and some utility
macros are not inherited as their functionality can be done in \LUA. The
number of backend interface commands has been reduced to a few. The
extensions are separated from the core (which we keep close to the
original \TEX\ core). Some mechanisms like expansion and protrusion can
behave different from the original due to some cleanup and optimization.
Some whatsit based functionality (image support and reusable content)
is now core functionality.
\stopitem
\startitem
The direction model and some other bits from \ALEPH\ RC4 (derived from
\OMEGA) is included. The related primitives are part of core \LUATEX\ but
at the node level directional support is no longer based on so called
whatsits but on real nodes. In fact, whatsits are now only used for
backend specific extensions.
\stopitem
\startitem
Neither \ALEPH's I/O translation processes, nor tcx files, nor \ENCTEX\
can be used, these encoding|-|related functions are superseded by a
\LUA|-|based solution (reader callbacks). In a similar fashion all file
\IO\ can be intercepted.
\stopitem
\startitem
We currently use \LUA\ 5.2.*. At some point we might decide to move to
5.3.* but that is yet to be decided. There are few \LUA\ libraries that
we consider part of the core \LUA\ machinery, for instance \type {lpeg}.
There are additional \LUA\ libraries that interface to the internals of
\TEX.
\stopitem
\startitem
There are various \TEX\ extensions but only those that cannot be done
using the \LUA\ interfaces. The math machinery often has two code paths:
one traditional and the other more suitable for wide \OPENTYPE\ fonts.
\stopitem
\startitem
The fontloader uses parts of \FONTFORGE\ 2008.11.17 combined with
additionaL code specific for usage in a \TEX\ engine. We try to minimize
specific font support to what \TEX needs: character references and
dimensions and delegate everything else to \LUA. That way we keep \TEX\
open for extensions without touching the core.
\stopitem
\startitem
The \METAPOST\ library is integral part of \LUATEX. This gives \TEX\ some
graphical capabilities using a relative high speed graphical subsystem.
Again \LUA\ is used as glue between the frontend and backend. Further
development of \METAPOST\ is closely related to \LUATEX.
\stopitem
\stopitemize
The yearly \TEXLIVE\ version is the stable version, any version between them are
to be considered beta. The beta releases are normally available via the \CONTEXT\
distribution channels (the garden and so called minimals).
\blank[1*big]
Hans Hagen, Harmut Henkel, \crlf
Taco Hoekwater \& Luigi Scarso
\blank[3*big]
\starttabulate
\NC Version \EQ \currentdate \NC \NR
\NC \LUATEX \EQ Snapshot \number\luatexversion.\luatexrevision \NC \NR
\NC \CONTEXT \EQ \contextversion \NC \NR
\stoptabulate
\stopchapter
\stopcomponent
|
